Aerobic plate count assays are an industry standard method for the enumeration of microbial products. Colony swarming among industrial Bacillus isolates on solid medium can impact a counting technician's interpretation of colony count, promote inter-technician variance and reduce the agreement of plate counts with growth-independent enumeration methods. In the present study, we examined swarming behavior among four industrial Bacillus species as a function of culture medium brand choice. Colony diameter for three Bacillus species was found to be influenced by culture medium brand, as was colony count interpretation among three out of four plate counting technicians. Estimations of Bacillus endospore concentration were likewise influenced by culture medium brand, leading to an increased incidence of QC failure for replicate samples of a Bacillus-based microbial product as a function of brand choice. Results suggest that culture medium brand choice may be an additional source of variance when plate counting is used for the enumeration of Bacillus-based microbial products. We recommend that plating medium brand availability in testing laboratories be considered by microbial product manufacturers when considering sources of variance in customer and regulatory laboratories.

中文翻译：

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培养基品牌的选择会影响工业芽孢杆菌分离株中的菌落聚集行为以及需氧平板计数的准确性。

好氧平板计数测定法是计数微生物产物的工业标准方法。在固体培养基上的工业芽孢杆菌分离株之间的菌落聚集会影响计数技术人员对菌落计数的解释，促进技术人员之间的差异，并减少与生长无关的枚举方法对板数的一致性。在本研究中，我们研究了四种工业芽孢杆菌物种之间的蜂群行为，作为培养基品牌选择的函数。发现三种芽孢杆菌属的菌落直径受培养基品牌的影响，四分之三的平板计数技术人员中的三名也受到菌落计数解释的影响。芽孢杆菌内生芽孢杆菌浓度的估算同样受培养基品牌的影响，导致基于品牌选择的芽孢杆菌属微生物产品重复样品的QC失败发生率增加。结果表明，当平板计数用于基于芽孢杆菌的微生物产品计数时，培养基品牌的选择可能是差异的另一个来源。我们建议微生物产品制造商在考虑客户和监管实验室的差异来源时，应考虑测试实验室中电镀介质品牌的可用性。